The present invention relates to the manufacture of parts under utilization of liquidous but curable material, particularly synthetic material and particularly under utilization of a mold or die having a cavity, there being a charge opening for feeding liquidous raw material into the mold which is then permitted to cure in situ; the part so made is subsequently removed. The invention relates specifically to a method of conducting procedures along the line outlined above as well as to equipment for carrying out such a method.
Synthetic material engineering involves, for example, the manufacture of parts from a material which, initially, is in some form of pasty or liquidous state but will cure, i.e. harden following, say, injection or other insertion of feed into a die, mold or the like. This procedure establishes a particularly contoured part. The molds thus used for this purpose usually include several releasable interconnected parts which are separated later in order to free the cured component so that the mold or die can be reused as soon as possible. Synthetic material, e.g. thermoplastic material but also wax or ceramic is envisioned as raw material.
As the die or mold cavity is charged with more or less liquidous raw material, the air occupying the mold cavity is displaced, a process which requires a certain period of time. Subsequent to filling, another period of time has to elapse to obtain curing and before the mold or die can be opened. The discharge of air is usually carried out through dividing surfaces, interfaces or the like which divide the interior cavity of the mold or die. In order to avoid the formation of air bubbles or other kind of gas bubbles and to reduce mold and die working cycle time, it is generally suggested to pressurize the liquidous charge and to force it into the die cavity under pressure. Also ducts are provided so that the air can completely discharge from the mold or die cavity, on charge thereof with liquidous raw material. This procedure requires the utilization of a press with a pressurized plunger, or an injection mold machine or the like wherein the performance determines the quality of the product as well as the duration of the cycle time. Also, certain gases may develop in the mold or die cavity and they act like a filling impediment, owing to the counterpressure they develop.